Cmake error undefined symbols for x86_64 - c++

Question

I am trying to compile the conv-net library in my mac osx yosemite with xcode. I even set the flags to libstdc++ still it is not linking properly.
i still get undefined symbols for architecture x86_64.
any help much appreciated.
sh-3.2# ./compile.sh
Building conv-net library
-- The C compiler identification is AppleClang 6.0.0.6000056
-- The CXX compiler identification is AppleClang 6.0.0.6000056
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Configuring done
WARNING: Target "testimg" requests linking to directory "/usr/local/Cellar/opencv/2.4.9/lib". Targets may link only to libraries. CMake is dropping the item.
WARNING: Target "testimg" requests linking to directory "/usr/local/Cellar/opencv/2.4.9/lib". Targets may link only to libraries. CMake is dropping the item.
WARNING: Target "testmnist" requests linking to directory "/usr/local/Cellar/opencv/2.4.9/lib". Targets may link only to libraries. CMake is dropping the item.
WARNING: Target "testmnist" requests linking to directory "/usr/local/Cellar/opencv/2.4.9/lib". Targets may link only to libraries. CMake is dropping the item.
-- Generating done
-- Build files have been written to: /var/tmp/conv-net-0.1-prealpha_buildroot
Scanning dependencies of target cvconvnet
[ 11%] Building CXX object CMakeFiles/cvconvnet.dir/src/cvsubsamplingplane.cpp.o
[ 22%] Building CXX object CMakeFiles/cvconvnet.dir/src/cvconvolutionplane.cpp.o
[ 33%] Building CXX object CMakeFiles/cvconvnet.dir/src/cvgenericplane.cpp.o
[ 44%] Building CXX object CMakeFiles/cvconvnet.dir/src/cvsourceplane.cpp.o
[ 55%] Building CXX object CMakeFiles/cvconvnet.dir/src/cvrbfplane.cpp.o
[ 66%] Building CXX object CMakeFiles/cvconvnet.dir/src/cvmaxplane.cpp.o
[ 77%] Building CXX object CMakeFiles/cvconvnet.dir/src/cvconvnetparser.cpp.o
[ 88%] Building CXX object CMakeFiles/cvconvnet.dir/src/cvfastsigmoid.cpp.o
[100%] Building CXX object CMakeFiles/cvconvnet.dir/src/cvconvnet.cpp.o
/Users/prabhubalakrishnan/Desktop/conv-net/src/cvconvnet.cpp:169:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
1 warning generated.
Linking CXX static library libcvconvnet.a
[100%] Built target cvconvnet
Scanning dependencies of target testimg
Linking CXX executable testimg
Undefined symbols for architecture x86_64:
"_main", referenced from:
implicit entry/start for main executable
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [testimg] Error 1
make[1]: *** [CMakeFiles/testimg.dir/all] Error 2
make: *** [all] Error 2
cp: testimg: No such file or directory
cp: testmnist: No such file or directory
ls: illegal option -- I
usage: ls [-ABCFGHLOPRSTUWabcdefghiklmnopqrstuwx1] [file ...]
This is my make file
cmake_minimum_required(VERSION 3.0)
PROJECT (CvConvolutionalNet)
set (CMAKE_CXX_FLAGS " -stdlib=libstdc++")
# IF() ENDIF() statements
SET(CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS true)
# Specify build-type as Debug if not specified already
IF (NOT CMAKE_BUILD_TYPE)
SET(CMAKE_BUILD_TYPE Debug)
ENDIF ()
# Produce verbose makefiles
# SET(CMAKE_VERBOSE_MAKEFILE ON)
# Sources for library
SET(CVCONVNET_SRCS
src/cvsubsamplingplane.cpp
src/cvconvolutionplane.cpp
src/cvgenericplane.cpp
src/cvsourceplane.cpp
src/cvrbfplane.cpp
src/cvmaxplane.cpp
src/cvconvnetparser.cpp
src/cvfastsigmoid.cpp
src/cvconvnet.cpp
)
# Sources for test files
SET(TESTIMG_SRCS tst/)
SET(TESTMNIST_SRCS tst/)
set (CV_H /usr/local/Cellar/opencv/2.4.9/include/opencv)
set (HIGHGUI_H src/include )
set (LIBCV /usr/local/Cellar/opencv/2.4.9/lib )
set (LIBHIGHGUI /usr/local/Cellar/opencv/2.4.9/lib )
# Here are common paths (in addition to default paths)
SET (INCLUDE_SEARCH_PATH
/usr/local/include /usr/include /usr/include/opencv/
/usr/include/opencv/ c:/program\ files/opencv/include
)
SET (LIBRARY_SEARCH_PATH
/usr/local/lib /usr/lib c:/program\ files/opencv/lib c:/windows/system32
)
# Find OpenCV and Expat
FIND_PATH(CV_H NAMES cv.h PATHS ${INCLUDE_SEARCH_PATH} )
FIND_PATH(HIGHGUI_H NAMES highgui.h PATHS ${INCLUDE_SEARCH_PATH} )
FIND_PATH(EXPAT_H NAMES expat.h PATHS ${INCLUDE_SEARCH_PATH} )
FIND_LIBRARY(LIBCV NAMES cv PATHS ${LIBRARY_SEARCH_PATH} )
FIND_LIBRARY(LIBHIGHGUI NAMES highgui PATHS ${LIBRARY_SEARCH_PATH} )
FIND_LIBRARY(LIBEXPAT NAMES expat PATHS ${LIBRARY_SEARCH_PATH} )
INCLUDE_DIRECTORIES(include/ ${CV_H} ${HIGHGUI_H} ${EXPAT_H})
# Here is out library
ADD_LIBRARY(cvconvnet STATIC ${CVCONVNET_SRCS})
# Here are our test programs
ADD_EXECUTABLE(testimg ${TESTIMG_SRCS})
ADD_EXECUTABLE(testmnist ${TESTMNIST_SRCS})
# Compiler options are different for Release and Debug
IF (CMAKE_BUILD_TYPE MATCHES Release)
# Highly optimized + cancel all assert()s
ADD_DEFINITIONS(-O3 -DNDEBUG)
ELSE ()
# Include debug info, profiling info, some text output
ADD_DEFINITIONS(-O -pg -g -DDEBUG)
# Set profiling for linker too
SET_TARGET_PROPERTIES(testmnist PROPERTIES LINK_FLAGS "-pg")
ENDIF ()
# We should link our test programs to libraries
TARGET_LINK_LIBRARIES(testimg cvconvnet ${LIBCV} ${LIBHIGHGUI} ${LIBEXPAT})
TARGET_LINK_LIBRARIES(testmnist cvconvnet ${LIBCV} ${LIBHIGHGUI} ${LIBEXPAT})

Answer 1

I fixed it by adding -c option in the compiler flags and it worked !!!!

Answer 2

The add_executable command takes a target name and a list of source files to be compiled. When you are creating a target for testimg you are passing it directory.
Use file(GLOB ...) command to gather all source files from directory into a list variable and pass it to add_executable call.